Tableau Dual Axis and Combo Charts

A dual axis chart places two measures in one view, each with its own vertical scale. Bars can show sales while a line shows profit margin. The combination reveals relationships that two separate charts hide.

Why Use Two Axes

Sales may run in the thousands while profit margin sits between 0 and 1. A single axis squashes the small numbers into a flat line. Two axes give each measure its own scale and keep both readable.

Single axis (hard to read)      Dual axis (clear)
Sales:  ||||||||||||||||        Sales (bars, left axis)
Margin: .                       Margin (line, right axis)

Build a Combo Chart Step by Step

Step 1: Create the First Chart

Drag Order Date to Columns and change it to Month. Drag Sales to Rows. Tableau draws a line chart.

Step 2: Add the Second Measure

Drag Profit to the right edge of the view. A dashed drop zone appears on the right side. Release the field there. A second axis appears with its own scale.

Step 3: Turn On Dual Axis

Right-click the right axis and choose Dual Axis. Both marks now share one canvas.

Step 4: Set Mark Types Separately

The Marks card now shows three sections: All, Sales, and Profit. Click the Sales section and change the mark type to Bar. Click the Profit section and keep the type as Line.

Resulting Layout

Sales ($)                                   Profit ($)
  |      ___                                    |
  |     |   |   ___        ___              /\  |
  |  ___|   |__|   |   ___|   |__      ____/  \_|
  | |   |   |  |   |__|   |   |  |    /
  +---Jan--Feb--Mar--Apr--May--Jun--->
       Bars = Sales    Line = Profit

Synchronize Axes

Synchronization forces both axes to use the same scale. Right-click the right axis and select Synchronize Axis. Use this option only when both measures share the same unit, such as Sales and Profit in dollars. Leave axes unsynchronized for mixed units, such as dollars and percentages.

Hide the Second Axis

Synchronized axes repeat the same numbers on both sides. Right-click the right axis and clear Show Header to remove the duplicate.

Combo Chart Without Dual Axis

Tableau offers a shortcut for measures that share a unit. Drag the second measure onto the same axis and drop it on top of the existing axis. A Measure Names field appears on the Columns or Rows shelf. Tableau shows both measures with one scale and builds a combined chart.

Popular Dual Axis Pairings

• Bars plus line: Monthly sales as bars with a profit margin line.
• Line plus line: Current year and previous year trends.
• Circle plus bar: Actual value as a bar with a target marked by a circle.
• Map plus map: A filled state map with city bubbles on top.

Design Guidelines

Color the Axes to Match the Marks

Color the axis title text the same as the mark color. Readers then know which scale belongs to which mark without checking a legend.

Keep the Measure Count Small

Two measures stay readable. Three or more measures crowd the view and confuse readers. Split extra measures into additional charts.

Beware of Misleading Scales

Different scales can imply a relationship that does not exist. Two lines that cross may only reflect scale choices. Label axes clearly and avoid stretching a scale to force a visual match.

Troubleshooting

• The right-click menu lacks Dual Axis: place the second measure on the opposite shelf edge, not inside the existing axis.
• Marks overlap awkwardly: set the line in front by moving that measure to the second position in the Marks layers.
• Dates misalign: use the same date level, such as Month, for both measures.

Summary

Dual axis charts layer two measures on separate scales. Build one chart, drag the second measure to the right edge, and enable Dual Axis. Set each mark type independently, and synchronize axes only when units match. Clear labels and matching colors keep the result honest and easy to read.